python-pandas的基本用法03

pandas的基本用法03-reindex()

    # -*- coding: utf-8 -*-     import numpy as np    from pandas import DataFrame, Series    from matplotlib.pyplot import axis    s = Series([1,2,3,4], index=['a','b','c','d'])    s2 = s.reindex(['a','b','c','d','e'], fill_value=0)    print s2    # a    1    # b    2    # c    3    # d    4    # e    0    # dtype: int64    s2 = s.reindex(['a','b','c','d','e'], method='ffill')    print s2    # a    1    # b    2    # c    3    # d    4    # e    4    # dtype: int64    print '对DataFrame重新指定索引'    f = DataFrame(np.arange(9).reshape(3, 3),              index = ['i1', 'i2', 'i3'],              columns = ['c1','c2','c3'])    print f    #     c1  c2  c3    # i1   0   1   2    # i2   3   4   5    # i3   6   7   8    f2 = f.reindex(['a','b','c', 'd'])    print f2    #  c1  c2  c3    # a NaN NaN NaN    # b NaN NaN NaN    # c NaN NaN NaN    # d NaN NaN NaN    print '重新指定column'    names = ['c1', 'c2', 'Tony']    print f.reindex(columns=names)    #     c1  c2  Tony    # i1   0   1   NaN    # i2   3   4   NaN    # i3   6   7   NaN    print '对DataFrame重新指定索引并指定填元素充方法'    print f    #     c1  c2  c3    # i1   0   1   2    # i2   3   4   5    # i3   6   7   8    f2 = f.reindex(index=['i1', 'i2', 'x'],                    method='ffill', columns=names)    print f2    #     c1  c2  Tony    # i1   0   1   NaN    # i2   3   4   NaN    # x    6   7   NaN    print f2.fillna(method='ffill', axis=1)    #     c1  c2  Tony    # i1   0   1     1    # i2   3   4     4    # x    6   7     7